Overweight and obesity are principal public health problems in the United States, and constitute two of the leading preventable causes of death. The primary outcomes for randomized clinical trials and epidemiological investigations addressing the obesity problem are caloric intake and caloric expenditure. Thus, accurate assessment of diet and physical activity (PA) behaviors is necessary for epidemiological, clinical, and research purposes. The validity of diet and PA outcomes is partially based on the accuracy of self-reported dietary portions and PA intensity. The primary goal of this investigation is to . improve dietary portion size and PA intensity measurement among older, overweight adults, using innovative, interactive computer technology and state-of-the-art statistical methods. Therefore, this project address several goals ofPAR-03-009 by addressing the assessment of both diet and physical activity, examining the older population, using a novel technology, and applying advanced statistical techniques. A CD-ROM will be developed based on available self-report instruments (Le., the NCI Fruit and Vegetable Screener, the Block Fat Screener, and the CHAMPS Activity Questionnaire for Older Adults) with the addition of engaging and instructive video to clarify serving sizes (diet) and intensity of activity (PA) and to provide immediate scoring and feedback. CD-ROM measurement will be compared to paper-and-pencil surveys as well as objective measures of diet (3-day dietary recalls; validation of portion sizes using food .models) and PA (activity monitors and diaries). In addition to standard, regression-based analyses, structural equation, latent class, and mixture modeling techniques will be used to account for measurement error and determine the existence of unobserved groups of respondents who report similarly on measures. A total of 220 heterogenous, older, overweight adults will be recruited for this project. Participants will be asked to complete the CD-ROM assessment, along with paper-and-pencil assessments and objective measurements, then will be retested 2 weeks later. Strengths of the proposed study include a team with a strong record in diet, PA, and CD-ROM intervention and assessment research as well as instrument development and statistical/methodological innovation; the use of new technology and analytic techniques; validation of self-report assessment procedures against more objective diet and physical activity measures. Relevance: This project addresses overweight and obesity, principal public health problems in the United States, and the leading preventable cause of death, by developing a more accurate and efficient assessment tool for dietary serving sizes [and PA intensity, an area routinely neglected in diet and PA research. This tool could be used for health research and clinical practice applications to serve the broad NIH goal of understanding control of obesity and health enhancement. [unreadable] [unreadable]